Hydraulic-based optimization methodologies are reliable and computationally effective techniques to determine a least capital cost design in water distribution networks. Some of these approaches rely on the calculation of the optimal hydraulic gradient surface (OHGS), a geometrical body that establishes the way in which the available hydraulic head should be spent within a network to ensure the calculation of a minimum capital cost diameter configuration. Given its amorphous morphology, the fractal dimension can be used as a parameter to understand the mathematical and physical properties of the OHGS. In the present study, the OHGS of a variety of theoretical and real water distribution systems is calculated by employing the optimal power use surface optimization methodology. The fractal analysis is then carried out by an image fractal dimension estimator algorithm, including the examination of random non-optimal designs. Moreover, the fractal dimension of the topology, flow, and energy distribution of the optimized networks was also calculated by a box-covering algorithm and compared to the fractal dimension of the OHGSs. The results show that the energy dissipation pattern in an optimal design exhibits certain fractal properties that can be used to distinguish it from more expensive diameter configurations. In addition, it was found that the fractal properties of the OHGS and of the topology, flow, and energy distribution inside the studied networks are somehow related. These findings may be applied in prospective optimization methodologies, operational improvement, or renewal procedures.